Against

In previous years, OnePlus hasn't been shy about pitching its mid-price phones as "flagship killers". To call the company self-assured would be something of an understatement, but this year's launch of the OnePlus 3 seemed a little more subdued. Perhaps uncharacteristically so.

In fact, if you didn't download the Loop VR app to watch the launch in virtual reality then there's a chance you will have missed the entire thing. Which is strange, because the OnePlus 3 is shaping up to be one of the best phones on the market this year, in particular at its £329 price point.

OnePlus 3 review: Design

Like the HTC One series and many other modern smartphones the OnePlus 3 is built from a single piece of aluminium. It has an attractive anodised finish, with its back slightly curved. The metal edges are ever-so-slightly rounded, too, with slim diamond-cut chamfers that catch the light just right to give a reflective glimmer every now and then.

At just 7.35mm thin the OnePlus 3 is a pleasure to hold. It feels like a much slimmer version of the Moto X Style from last year. It's a similar width and height, with a 5.5-inch screen to boot, but is thinner overall. Despite that large display, the phone is pretty easy to grip, although it's hard to use one-handed.

The choice of material — which looks virtually identical to the iPhone 6S's Space Grey — isn't the only change from last year's OnePlus 2: the 3's volume rocker switch has now switched to the left edge (when facing), where it sits below the notification priority switch. Which makes sense, since their functions are related. All the buttons are well constructed, easily reachable with an index finger or thumb, and give just the right amount of feedback to give that tactile affirmation our senses often crave.

That leaves the dual-SIM tray and the power button to occupy the phone's right edge, while the bottom edge features a USB Type-C connector flanked by a 3.5mm jack and six individually machined holes for the mono loudspeaker.

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This lack of stereo front-facing speakers is definitely a drawback. Sound firing sideways from the bottom edge will never sound as good as sound being blasted towards your ears. When gaming it's far too easy to cover the loudspeaker with your palm, thus muting the sound. Watching movies and the same can be true.

Overall, though, considering the £329 asking price, the OnePlus 3's build is every bit the flagship. However, there's no option to expand the 64GB on-board storage via microSD — which is arguably part and parcel of the unibody design.

OnePlus 3 review: Display

Compared to the AMOLED panels of high-end Nexus and Galaxy phones, the earlier OnePlus 2's LCD-based display was a little lacking in colour and contrast. Sure, it was crisp and clean, but lacked life.

The OnePlus 3 changes that. Its 5.5-inch Full HD AMOLED panel on the front is full of colour, has high contrast levels and still retains the crispness of the former phones. The display also features a dual-polarising layer which OnePlus claims makes the screen more easily visible when outdoors in bright daylight — it works well in practice too, although you might struggle to see the screen if its surface is angled directly towards the sun.

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Likewise, indoors, even with the brightness set at just 50 per cent, the screen looks very bright. What's more, its bezel is nice and slim, so the content on screen dominates the front panel.

Corning Gorilla Glass 4 covers the screen, which is so closely laminated that content seems to almost float on the surface of the glass. Adding a final flourish, there's a subtle curve in the glass, all the way around the surface towards the edges.

The screen's one negative is that it's not Quad HD resolution (2160 x 1440 pixels) — a point that we've raised time and again with earlier models, but that point isn't a total killer. It's not even a partial killer, really, despite it being one of the main things absent that the "true flagships" have. Still, unless you're using VR headsets, such as the Loop VR, you're unlikely to notice the lower resolution, unless you happen to use your phone pressed against your face.

OnePlus 3 review: Software

As has been customary for OnePlus since the split from its Cyanogen-based software on the OnePlus One, the OnePlus 3 runs OxygenOS which, this year in version 3, is built on top of Android Marshmallow. One of the notable things about OnePlus' software is that it looks and feels very much like regular stock Android, but with a few tweaks.

The phone comes with a bespoke version of SwiftKey's keyboard pre-installed, which has great autocorrect and predictive text skills. And then there's Shelf, the screen that sits to the left of the first home screen: here you can type memos and quickly get in touch with your favourite contacts or launch your most-used apps, plus view the weather, date and reminders. It's potentially useful, but can be switched off if you prefer.

Perhaps the most important difference between stock Android and OxygenOS is the level of customisation you get. Using the built-in software tools you can set the entire system to Dark Mode (a system-wide dark theme), customise LED notifications choosing different colours for specific app notifications, swap around icons in the status bar at the top of the screen, or swap between hardware or software buttons.

Other customisation options include changing the app icon size on screen, choosing how many columns of apps you want in the app drawer, and whether you want a semi-transparent greyscale Google search bar, or an opaque one with full Google colouring.

There are also a number of different gestures you can use from the launch screen. For example, you can launch the camera by drawing an "O" on the screen in standby, or draw a "V" to switch on the torch/flashlight. You'll probably never use these gestures, but they're there.

OnePlus 3 review: Performance

Inside the OnePlus 3 there's a top-of-the-line Snapdragon 820 processor. It's quad-core and is paired with a massive 6GB of RAM to ensure that you never, ever feel as though the phone is sluggish.

Since 6GB RAM is still new in the Android scene, OnePlus has only optimised a few of its built-in modules to make use of it, so most of the time you won't be making use of the entire memory. The camera app, for instance, can use all of the phone's memory. It may seem an odd decision include so much RAM and not always fully utilise it, but at this time using all 6GB would have a detrimental affect on battery life. What's more, the move puts the OnePlus 3 in a great place for future-proofing.

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But even in its current position the OnePlus 3 feels super sleek in use. It flies in and out of apps, scrolling up and down lists, and around the web with consummate ease. Part of that is down to the software, of course, but part because the phone has the guts of a proper powerful phone.

Even when gaming, generally speaking, animations are very smooth and stutter-free. There has been a very minor issue with the sound syncing on Real Racing 3, but that was the only title that struggled from what we've seen, and that's perhaps down to the app rather than the phone's hardware.

Like last year's OnePlus 2, the OnePlus 3 comes with a fingerprint scanner — but it's much improved, responding fast and unlocking in the blink of an eye. We've gone digging into hardware specifications and found the scanner used here is the same as found in the Oppo F1 Plus, which we found very impressive too.

And as an NFC chip has finally been added to this OnePlus — that's something the OnePlus 2 bizarrely lacked — the scanner can be used for contactless payment options through Android Pay or, if you use Barclays, using the mobile banking Android app.

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OnePlus 3 review: Battery life

To make sure it keeps all that power going all day, there's a 3,000mAh battery built into the body. With Android Marshmallow's built-in Doze standby power management and OnePlus's own optimisations, the OnePlus 3 easily manages a full day on a single charge. While it's not quite the two-day battery promised by the manufacturer, it can make it to a day and a half fairly comfortably.

Like many other Marshmallow phones, Google's Doze mode means you can leave the OnePlus 3 in standby overnight and you'll only lose a few per cent from the battery level. Not that you have to, mind, as the OnePlus allows you to set an alarm and have it boot-up the phone. So, if you'd rather, you can set your alarm and then just switch the phone off when you go to bed.

What's more, even if the OnePlus 3 does run out of juice, it has Dash Charge technology — which works the same way as VOOC flash charging, as used by the Oppo F1 Plus. You can get up to 60 per cent charge from just 30-minutes plugged into the wall, even if you're using the phone at the same time. In most cases, charging from zero to full takes around 75-minutes. It can do this without the phone heating up too much too. The secret behind this is in the thick USB cable which dissipates heat as it's pumping 20W of power to the phone.

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OnePlus 3 review: Camera

OnePlus promised a lot with its camera at launch. Spec-wise, it's a 16MP Sony sensor with f/2.0 aperture and 4K video recording capability so, on paper at least, it certainly seems more than capable of challenging the best of them.

There's something called Dynamic Denoise, which helps smooth-out any graininess you find in typical low-light shots; HD mode for boosting sharpness and clarity; and HDR mode for producing balanced exposures even in harsh lighting conditions. Sadly, you can't use HDR and HD modes at the same time.

The only problem with all of this is that it doesn't seem to work perfectly. Those hoping for a camera capable of taking on the Galaxy S7 or S7 Edge might be a little disappointed. Sometimes the OnePlus 3 struggles to focus in automatic mode, too, especially when taking close-up shots.

Once you do acquire focus and take the shot, the camera is capable of producing some attractive images. Automatic mode does a great job of dealing with varying light levels, ensuring that nothing is over-exposed or too harsh in bright daylight. It snaps them really quickly too. Images in good daylight have a deft balance of colour, but the ferocity of the de-noise algorithm seems too much. Low-light throws up its share of issues, but we've snapped some lovely long-exposures at night.

You can manually change the shutter speed and focus to get the ideal shot, as well as customising the brightness and exposure if needed. And, to ensure that you get a great shot as often as possible, it features both optical image stabilisation to deal with hand-shakiness when taking photos, and electronic image stabilisation for video purposes.

Speaking of video, its 4K recording is generally good, coping well when focusing automatically on objects nearby and further away. As is the case with many smartphone cameras, though, the OnePlus 3 sometimes locks on to the background rather than the foreground, but you can select focus points manually during shooting.

Slow-motion video is another nice touch, but doesn't offer the same kind of manual trimming you get in an iPhone or Samsung device. It just records the whole thing in a high frame-rate and saves that entire clip.

Verdict

As an overall package, as is always the case with OnePlus phones, the third-generation flagship killer is incredible value for money. At £329 it offers many of the same features and specifications of phones twice the price.

The all-metal finish of the OnePlus 3 is sleek, sturdy and makes the phone seem like a genuinely premium device. It's a far cry from the plastic-backed phones of previous years without a giant price hike. The screen is rather fantastic, too, with popping colours, deep blacks and sharp detail that AMOLED offers — even if it lacks a truly flagship Quad HD resolution.

OnePlus has shied away from calling the OnePlus 3 a "flagship killer" this year. But we don't think it should have. This phone lays down a marker for what you can get for around £330. There is some competition from the Oppo F1 Plus and Vodafone Smart Platinum 7, but given the option we'd hands-down plump for the OnePlus every time.

Update: Originally the OnePlus 3 was £309. A £20 increase ocurred for UK customers from 11 July, with Brexit and the resulting market instability cited as the reason.